1. Field of the Invention
The present invention relates to a cam mechanism for operating plungers of a plunger pump and a liquid sending pump having the cam mechanism. Particularly, the cam mechanism relates to one having a lubricant supply mechanism for supplying lubricant to contact portions between cams and cam followers.
2. Description of the Related Art
As a liquid sending pump used for sending a solution such as mobile phase in liquid chromatograph, there is a pump formed to convert rotary movement of a motor into reciprocating movement in a certain direction by a cam mechanism to drive plungers (see Japanese Patent Application Laid-Open No. 7-318548, for example). Base end portions of the plungers are retained by cam followers and the cam followers are displaced following peripheral faces of the cams to thereby reciprocate the plungers in a certain direction. When tip ends of the plungers are inserted into pump chambers in pump heads and slide, the solution is taken into the pump chambers and discharged from the pump chambers.
In such a liquid sending pump, mechanisms for supplying lubricant to contact portions between the cams and the cam followers are provided in order to minimize a load on the motor so that rotation of the motor is controlled with high accuracy. A common lubricant supply mechanism is one formed to apply the lubricant on the peripheral face of the cam by retaining a sponge impregnated with the lubricant in a position in contact with the peripheral face of the cam.
However, part of the lubricant applied on the peripheral face of the cam is pushed out of the contact portion between the cam and the cam follower, flows to side faces of the cam, and is wasted without utilized as the lubricant. In prior art, the lubricant flowing to the side faces of the cam cannot be utilized and some of the lubricant impregnated into the sponge of the lubricant supply mechanism is wasted.